Substrates that possess water and oil repellence are desirable in many textile applications, and have been manufactured for some time. Water and oil repellence generally means the ability of the textile to block water and oil from penetrating into the fibers of the textile. Examples include rainwear, upholstery applications, carpet, apparel and the like. These articles are generally manufactured by applying suitable fluorocarbon polymers to the surface of the textile, followed by drying and curing the substrate to properly align the fluorochemical segments of the polymers. Fluorochemicals also help to reduce the tendency of soil, oil, and water to adhere to the fibers of the substrate. These fluorochemicals typically include a fluorinated component and a nonfluorinated polymeric backbone. The important feature of the polymeric backbone is that it is capable of yielding a durable treatment on the surface of the fiber.
Similarly, substrates possessing acceptable soil release characteristics are known. As used herein, soil releasability is defined as the degree to which a soiled substrate approaches its original, unsoiled appearance as a result of a care procedure. Generally, soil release properties are obtained increasing polarity and/or hydrophilicity of textile substrates so that interactions with water and detergents are favoured. Examples include natural fibers such as cotton, hydrophilic synthetic fibers such as nylon and acrylic, and synthetic polymers that have been modified to improve soil releasability by the application of hydrophilic soil release polymers. Suitable soil release polymers include carboxylic acid containing copolymers, sulfonic acid containing copolymers, ethoxylated polyesters, certain polyacrylamide polymers and certain cellulose derivatives.
Extensive efforts have been made to produce a textile substrate having the properties of durable water and oil repellence, as well as improved durable soil release characteristics.
Generally, treatments are available to impart either one of these properties to a textile, but it has proven difficult to provide both properties to a single substrate for any appreciable length of time.
Natural fibers such as cotton and wool exhibit little water/oil repellence, but when they do become soiled, they are readily cleaned, thus exhibiting a high level of soil releasability. Many synthetics, notably polyester, exhibit a low level of soil releasability. Thus, the trend of producing textiles having a natural/synthetic blend of fibers tends to aggravate the situation because such blends are easily soiled and the absorbed soil is difficult to wash out.
Fluorinated (meth)acrylic polymers have been proposed in the past for increasing stain resistance and providing textile substrates with a inert fluorocarbon-like outer surface, oleophobic and hydrophobic. Examples of such fluorinated (meth)acrylic polymers are notably described in U.S. Pat. No. 2,803,615 (3M COMPANY) Aug. 20, 1957, U.S. Pat. No. 2,995,542 (3M COMPANY) Aug. 8, 1961, U.S. Pat. No. 3,356,628 (3M COMPANY) May 12, 1967, U.S. Pat. No. 4,525,423 (3M COMPANY) Jun. 25, 1985, U.S. Pat. No. 4,529,658 (3M COMPANY) Jul. 16, 1985, U.S. Pat. No. 2,839,513 (3M COMPANY) Jun. 17, 1958 and U.S. Pat. No. 3,814,741 (MONTECATINI EDISON) Jun. 4, 1974.
However, these and other fluorocarbon polymer of the prior art tend to make the soil release properties worse because the aqueous washing medium cannot properly wet the substrate, and hence cannot remove the stains. Conversely, the addition of hydrophilic soil release polymers tends to enhance the soil release characteristics, but limits the ability of the textile to resist and repel water and oil based liquids.
Examples of such copolymers include SCOTCHGUARD® FC-248 from 3M, and REPEARL® F-84, marketed by Mitsubishi Chemical. These products provide a certain degree of water/oil repellency and a certain soil release to many substrates, but the oil/water repellency and soil release capabilities are lower from those obtained, respectively, with traditional fluorochemical polymer treatments and with hydrophilic soil release polymers or surfactants treatments. Further, the copolymers tend to lack durability for many applications. Durability is defined herein as retaining an acceptable level of the desired function through a reasonable number of care cycles.
One method for treating substrates to simultaneously impart both of these characteristics has been to use copolymers containing fluorocarbon oil/water repellent segments and hydrophilic soil release segments.
As mentioned above, fluorocarbons have been applied to textiles in attempts to solve this problem by providing limited protection against oily stains due to the oleophobic properties of most fluorocarbons.
U.S. Pat. No. 6,500,894 (AUSIMONT SPA (IT)) Dec. 31, 2002 discloses aqueous dispersions for oil&water repellence treatments of textiles, comprising a mixture of the following fluorinated polymers: A) (meth)acrylic (co)polymers containing fluorine, and B) cationic ionomers of fluorinated polyurethanes based on (per) fluoropolyethers. These compositions possess relatively poor oil&water repellence and stain release capabilities. Moreover, their durability is not satisfactory.
EP 1327644 A (SOLVAY SOLEXIS SPA (IT)) Jul. 16, 2003 discloses a cationic fluorinated polyurethane polymer comprising perfluoropolyoxyalkylene chains having terminal capped NCO groups for surface hydro- and oil-repellence treatment of textiles. While performances are relatively poor, durability is unsatisfactory.
There is thus still a need in the art for a composition able to imparting to textile substrates at the same time durable and outstanding anti-stain capabilities (i.e. water and oil-repellence) and durable and outstanding soil release properties.